Radio frequency identification technology (RFID) and, more specifically, near field communication technology (NFC), have proven to be of particular value for setting up Wi-Fi networks and for pairing Bluetooth devices. Furthermore, these technologies can be of high value in the field of smart buildings. For example, they can be used to simplify the commissioning of wireless devices in a smart building.
In this context, the term “commissioning” is used to refer to operations that relate to the configuration of devices, such as establishing a network connection between devices, establishing a control relationship between devices and localizing devices in an environment.
In a typical commissioning procedure two wireless devices are brought in close proximity of each other or in direct contact with each other. Subsequently, these devices establish a secure network connection and/or a control relationship between each other. Network parameters, including encryption keys, are exchanged over a very short distance which makes eavesdropping difficult. NFC technology, which typically requires distances of a few centimeters, provides a particular advantage in this respect. Another advantage of NFC technology is the so-called ease-of-install; NFC technology makes commissioning procedures easy and intuitive to perform and it reduces the error-proneness of these procedures.
As a result, the Wi-Fi Alliance (http://www.wi-fi.org/) has standardized NFC as optional means for Wi-Fi Simple Configuration (WSC), formerly known as Wi-Fi Protected Setup (WPS). This has been described in the document “Wi-Fi Simple Configuration, Technical Specification”, version 2.0.0, December 2010 by the Wi-Fi Alliance.
In accordance with this known commissioning procedure an RFID tag is physically attached to the housing of a first wireless device. The RFID tag contains contact data of the first wireless device, such as its Media Access Control (MAC) address. In order to integrate the first wireless device into a Wi-Fi network, a second wireless device is equipped with an RFID reader unit. The second wireless device is brought into close proximity of the first wireless device in order to enable the RFID reader unit to read out the contact data of the first wireless device from the RFID tag. Then, the second wireless device may use the contact data in so-called in-band communication over the Wi-Fi network in order to integrate the first wireless device in a secure manner into the network.
In a similar way Bluetooth Easy Pairing enables establishing a secure Bluetooth connection between two devices, for example a phone and a headset. In this case not only a network connection is set up, but also a control relationship is established. For example, the audio stream from the phone may be routed to the headset and the headset may transmit commands back to the phone.
Both the Wi-Fi and the Bluetooth examples are based on RFID technology, in particular NFC technology. Specific details of the NFC communication involved have been described in the document “Connection Handover, Technical Specification” by the NFC Forum, version 1.2, July 2010 (http://www.nfc-forum.org/).
Another example of the use of RFID/NFC technology to establish a control relationship between devices is described in patent application WO 2010/032227 A1, filed by NXP Semiconductors and published on 25 Mar. 2010.
WO 2010/032227 A1 discloses a method for controlling controllable devices, such as lamp units that are installed in a building, with a plurality of control interface units, such as light switches. Each control interface unit has a receptor, such as a light switch, for receiving user actuations. Addresses to be used for selective transmission of messages to controllable devices are established by enabling the control interface unit that should control a controllable device to read a tag on or in the controllable device. The control interface units each have their own tag reader capable of reading the tag when the tag is in proximity of the control interface unit. The controllable devices are brought into the proximity of a selected one of the control interface units before installation of the controllable device, in order to indicate that the controllable device has to be controlled by actuation of a receptor of the selected one of the control interface units. The tag of the controllable device is read from the selected one of the control interface units. Information from the tag is automatically used to establish destinations to be used for messages from the selected one of the control interface units in response to future detection of user actuation of the receptor of the selected one of the control interface units. Subsequently, the controllable device may be installed in the building at a location outside said proximity.
Although these examples clearly show that RFID/NFC technology provides important advantages when it is used to commission wireless devices of the kind set forth, there are still a number of shortcomings which hinder large-scale deployment thereof. For example, a typical prior art procedure for connecting a Bluetooth headset with a Bluetooth-enabled mobile phone involves switching on the headset by pushing its power button and bringing it in close proximity of the phone. The procedure requires two end-user actions: (1) switching on the headset and (2) bringing the phone and the headset in close proximity of each other. It is essential that the headset is switched on before or while the phone is in close proximity of the headset; otherwise the procedure will fail. This procedure is not user-friendly and prone to errors. For instance, forgetting to switch on the headset before touching the phone is a mistake which is easily made. Therefore, a bad overall end-user experience may be the result. Furthermore, the headset needs to be equipped with a power button which increases its costs and limits the freedom to design it. It will be appreciated that the headset cannot stay powered all the time in view of the limited capacity of its battery, so it must be brought in a low-power or sleep mode when it is not in use.
A similar problem occurs when securely setting up a Wireless Sensor Network (WSN) comprising of wireless sensor nodes. Wireless sensor nodes are energy-frugal devices (having an average power consumption of less than 100 μW) that may extract the energy required for their operation from their environment. The extremely low average power consumption is achieved through duty cycling, i.e. the device wakes up, for example, every few minutes to perform some measurements and transmit a few tens of bytes and subsequently goes back to sleep. The total duration of the active period may be no more than a few milliseconds.
Wireless sensor nodes are able to configure themselves automatically in a WSN, but this procedure is not secure. For example, in home automation systems it is not possible to distinguish between sensor nodes belonging to one's own house and the neighbor's house. One would like to configure a network comprising the sensor nodes in one's own house, but not those in the neighboring houses. Furthermore, privacy and security present a problem. For example, one doesn't want one's presence to be inferred from wireless sensor messages, and one doesn't want someone to hack one's home automation system. Finally, although (unsecure) network joining may take place automatically, automation is less trivial for other aspects of commissioning such as establishing control relationships between devices and localization of devices.
Also in this case NFC-based “touching” enables easy and secure commissioning of a wireless sensor node. For example, an NFC-enabled installation device may be used to “touch” a sensor node which has an RFID tag attached to it in order to make it join the WSN in a secure manner, to establish a control relationship and/or to localize it. However, since the sensor node may only be in an active state once every few minutes it is necessary to explicitly force it to become active, for instance by pressing a button. Again, the button complicates the commissioning procedure and increases the cost of the sensor node. Furthermore, adding a button may be impractical in view of the small form factor of the sensor node. Also, the time span between a user pushing the button and subsequently bringing the installation device and the wireless sensor node in close proximity of each other (typically in the order of seconds) may already be too long considering the very limited energy resources of the wireless sensor node.
Therefore, there exists a need to simplify the procedures for commissioning devices of the kind set forth.